Add ghostel-debug-info and resize/redraw logging

ghostel-debug-info: interactive command that dumps Emacs version,
system info, native module version (with mismatch warning), terminal
state (DEC 2026, pending output, window-start), and settings into
*ghostel-debug* for pasting into bug reports.

ghostel-debug-start/stop: now also logs resize events (old/new
dimensions, timing) and redraw decisions (skip vs execute, DEC 2026
state, force flag, buffer size delta, window-start before/after).

Author: dakra

ghostel-debug.el

@@ -31,20 +31,33 @@
 ;;; Code:
 
 (require 'cl-lib)
+(require 'lisp-mnt)
+(require 'ghostel)
+
+(declare-function ghostel--module-version "ghostel-module")
+(declare-function ghostel--mode-enabled "ghostel-module")
 
 (defvar ghostel-debug--log-buffer nil
   "Buffer used for ghostel debug logging.")
 
+;;;###autoload
 (defun ghostel-debug-start ()
-  "Start logging ghostel filter calls to *ghostel-debug* buffer."
+  "Start logging ghostel events to *ghostel-debug* buffer.
+Logs filter calls, key sends, resize events, redraw decisions
+\(including DEC 2026 skip/force), and `window-start' anchoring."
   (interactive)
   (setq ghostel-debug--log-buffer (get-buffer-create "*ghostel-debug*"))
   (with-current-buffer ghostel-debug--log-buffer
     (erase-buffer)
     (insert "=== Ghostel Debug Log ===\n\n"))
+  ;; Data path
   (advice-add 'ghostel--filter :before #'ghostel-debug--log-filter)
   (advice-add 'ghostel--send-key :before #'ghostel-debug--log-send)
   (advice-add 'ghostel--send-encoded :before #'ghostel-debug--log-encoded)
+  ;; Render path
+  (advice-add 'ghostel--delayed-redraw :around #'ghostel-debug--log-redraw)
+  (advice-add 'ghostel--window-adjust-process-window-size
+              :around #'ghostel-debug--log-resize)
   (when (fboundp 'ghostel--enable-vt-log)
     (ghostel--enable-vt-log))
   (message "ghostel-debug: logging started, check *ghostel-debug* buffer"))
@@ -55,6 +68,9 @@
   (advice-remove 'ghostel--filter #'ghostel-debug--log-filter)
   (advice-remove 'ghostel--send-key #'ghostel-debug--log-send)
   (advice-remove 'ghostel--send-encoded #'ghostel-debug--log-encoded)
+  (advice-remove 'ghostel--delayed-redraw #'ghostel-debug--log-redraw)
+  (advice-remove 'ghostel--window-adjust-process-window-size
+                 #'ghostel-debug--log-resize)
   (when (fboundp 'ghostel--disable-vt-log)
     (ghostel--disable-vt-log))
   (message "ghostel-debug: logging stopped"))
@@ -103,6 +119,63 @@ _PROC is ignored."
                       (format-time-string "%T.%3N")
                       key-name mods utf8)))))
 
+(defun ghostel-debug--log-redraw (orig-fn buffer)
+  "Log redraw decisions: skip vs execute, DEC 2026 state, timing.
+ORIG-FN is `ghostel--delayed-redraw', BUFFER is the target buffer."
+  (when ghostel-debug--log-buffer
+    (let (sync force win-start pt buf-size)
+      (when (buffer-live-p buffer)
+        (with-current-buffer buffer
+          (setq sync (and ghostel--term
+                          (ghostel--mode-enabled ghostel--term 2026)))
+          (setq force ghostel--force-next-redraw)
+          (setq buf-size (buffer-size))
+          (setq pt (point))
+          (let ((win (get-buffer-window buffer)))
+            (when win
+              (setq win-start (window-start win))))))
+      (let ((t0 (current-time)))
+        (funcall orig-fn buffer)
+        (let ((elapsed (* 1000 (float-time (time-subtract (current-time) t0))))
+              pt-after win-start-after buf-size-after)
+          (when (buffer-live-p buffer)
+            (with-current-buffer buffer
+              (setq pt-after (point))
+              (setq buf-size-after (buffer-size))
+              (let ((win (get-buffer-window buffer)))
+                (when win
+                  (setq win-start-after (window-start win))))))
+          (with-current-buffer ghostel-debug--log-buffer
+            (goto-char (point-max))
+            (if (and sync (not force))
+                (insert (format "[%s] REDRAW: SKIPPED (DEC2026 active, force=nil)\n"
+                                (format-time-string "%T.%3N")))
+              (insert (format "[%s] REDRAW: %.1fms force=%s dec2026=%s buf=%d→%d pt=%d→%d wstart=%s→%s\n"
+                              (format-time-string "%T.%3N")
+                              elapsed force sync
+                              buf-size buf-size-after
+                              pt pt-after
+                              win-start win-start-after)))))))))
+
+(defun ghostel-debug--log-resize (orig-fn process windows)
+  "Log resize events with old/new dimensions and timing.
+ORIG-FN is `ghostel--window-adjust-process-window-size'.
+PROCESS and WINDOWS are passed through."
+  (let* ((old-rows (when (buffer-live-p (process-buffer process))
+                     (buffer-local-value 'ghostel--term-rows (process-buffer process))))
+         (t0 (current-time))
+         (size (funcall orig-fn process windows))
+         (elapsed (* 1000 (float-time (time-subtract (current-time) t0)))))
+    (when ghostel-debug--log-buffer
+      (with-current-buffer ghostel-debug--log-buffer
+        (goto-char (point-max))
+        (insert (format "[%s] RESIZE: %sx%s → %sx%s (%.1fms)\n"
+                        (format-time-string "%T.%3N")
+                        (and old-rows (cdr size)) old-rows
+                        (car size) (cdr size)
+                        elapsed))))
+    size))
+
 
 ;;; Typing latency measurement
 
@@ -221,5 +294,129 @@ The latency breakdown shows:
         (insert "\n")))
     (message "ghostel-debug: latency report ready in *ghostel-debug*")))
 
+
+;;; Environment diagnostics
+
+;;;###autoload
+(defun ghostel-debug-info ()
+  "Display diagnostic info about the ghostel environment.
+Collects Emacs version, system info, native module state, terminal
+state, and settings into *ghostel-debug* for pasting into bug reports."
+  (interactive)
+  (let ((out (get-buffer-create "*ghostel-debug*"))
+        (ghostel-buf (when (derived-mode-p 'ghostel-mode) (current-buffer))))
+    (with-current-buffer out
+      (let ((inhibit-read-only t))
+        (erase-buffer)
+        (insert "=== ghostel-debug-info ===\n\n")
+        ;; System
+        (insert "--- System ---\n")
+        (insert (format "Emacs version:       %s\n" emacs-version))
+        (insert (format "System type:         %s\n" system-type))
+        (insert (format "System config:       %s\n" system-configuration))
+        (insert (format "Window system:       %s\n" (or window-system "terminal")))
+        (when (display-graphic-p)
+          (insert (format "Display pixel size:  %sx%s\n"
+                          (display-pixel-width) (display-pixel-height)))
+          (insert (format "Char size:           %dx%d px\n"
+                          (frame-char-width) (frame-char-height))))
+        (insert (format "Native comp:         %s\n"
+                        (if (and (fboundp 'native-comp-available-p)
+                                 (native-comp-available-p))
+                            "yes" "no")))
+        ;; Ghostel versions
+        (insert "\n--- Ghostel ---\n")
+        (let* ((lib (locate-library "ghostel"))
+               (dir (and lib (file-name-directory lib))))
+          (insert (format "Package version:     %s\n"
+                          (condition-case nil
+                              (lm-version (locate-library "ghostel.el" t))
+                            (error "Unknown"))))
+          (insert (format "Min module version:  %s\n" ghostel--minimum-module-version))
+          (insert (format "Library path:        %s\n" (or lib "not found")))
+          ;; Native module
+          (let ((mod-loaded (fboundp 'ghostel--module-version)))
+            (insert (format "Module loaded:       %s\n" (if mod-loaded "yes" "no")))
+            (when mod-loaded
+              (let ((mod-ver (ghostel--module-version)))
+                (insert (format "Module version:      %s\n" mod-ver))
+                (unless (string= mod-ver ghostel--minimum-module-version)
+                  (insert (format "  *** VERSION MISMATCH: elisp expects >= %s, module is %s ***\n"
+                                  ghostel--minimum-module-version mod-ver)))))
+            (when dir
+              (let ((mod-file (expand-file-name
+                               (concat "ghostel-module" module-file-suffix) dir)))
+                (if (file-exists-p mod-file)
+                    (let ((attrs (file-attributes mod-file)))
+                      (insert (format "Module file:         %s\n" mod-file))
+                      (insert (format "Module size:         %s bytes\n"
+                                      (file-attribute-size attrs)))
+                      (insert (format "Module modified:     %s\n"
+                                      (format-time-string
+                                       "%Y-%m-%d %H:%M:%S"
+                                       (file-attribute-modification-time attrs)))))
+                  (insert (format "Module file:         NOT FOUND in %s\n" dir)))))))
+        ;; Terminal state
+        (insert "\n--- Terminal State ---\n")
+        (if ghostel-buf
+            (let (info)
+              (with-current-buffer ghostel-buf
+                (setq info
+                      (list :buffer (buffer-name)
+                            :rows ghostel--term-rows
+                            :buf-size (buffer-size)
+                            :buf-lines (count-lines (point-min) (point-max))
+                            :point (point)
+                            :term ghostel--term
+                            :force ghostel--force-next-redraw
+                            :pending (length ghostel--pending-output)
+                            :timer (and ghostel--redraw-timer t)
+                            :copy ghostel--copy-mode-active
+                            :dec2026 (and ghostel--term
+                                          (ghostel--mode-enabled ghostel--term 2026))))
+                (let ((win (get-buffer-window ghostel-buf)))
+                  (when win
+                    (setq info (plist-put info :win-w (window-body-width win)))
+                    (setq info (plist-put info :win-h (window-body-height win)))
+                    (setq info (plist-put info :win-start (window-start win)))
+                    (setq info (plist-put info :win-end (window-end win t))))))
+              (insert (format "Buffer:              %s\n" (plist-get info :buffer)))
+              (insert (format "Term rows:           %s\n" (plist-get info :rows)))
+              (insert (format "Buffer size:         %d chars, %d lines\n"
+                              (plist-get info :buf-size) (plist-get info :buf-lines)))
+              (insert (format "Point:               %d\n" (plist-get info :point)))
+              (if (plist-get info :win-w)
+                  (progn
+                    (insert (format "Window body:         %dx%d (cols x rows)\n"
+                                    (plist-get info :win-w) (plist-get info :win-h)))
+                    (insert (format "Window start:        %d\n" (plist-get info :win-start)))
+                    (insert (format "Window end:          %d\n" (plist-get info :win-end))))
+                (insert "Window:              not displayed\n"))
+              (if (plist-get info :term)
+                  (progn
+                    (insert (format "DEC 2026 (sync):     %s\n"
+                                    (if (plist-get info :dec2026) "ACTIVE" "off")))
+                    (insert (format "Force next redraw:   %s\n" (plist-get info :force)))
+                    (insert (format "Pending output:      %s chunks\n" (plist-get info :pending)))
+                    (insert (format "Redraw timer:        %s\n"
+                                    (if (plist-get info :timer) "pending" "none")))
+                    (insert (format "Copy mode:           %s\n"
+                                    (if (plist-get info :copy) "active" "off"))))
+                (insert "Term handle:         nil (no terminal)\n")))
+          (insert "(not in a ghostel buffer)\n"))
+        ;; Settings
+        (insert "\n--- Settings ---\n")
+        (insert (format "timer-delay:         %s\n" ghostel-timer-delay))
+        (insert (format "full-redraw:         %s\n" ghostel-full-redraw))
+        (insert (format "adaptive-fps:        %s\n" ghostel-adaptive-fps))
+        (insert (format "immediate-threshold: %s\n" ghostel-immediate-redraw-threshold))
+        (insert (format "immediate-interval:  %s\n" ghostel-immediate-redraw-interval))
+        (insert (format "scroll-conservatively: %s\n"
+                        (if ghostel-buf
+                            (buffer-local-value 'scroll-conservatively ghostel-buf)
+                          scroll-conservatively)))))
+    (display-buffer out)
+    (message "Debug info written to *ghostel-debug*")))
+
 (provide 'ghostel-debug)
 ;;; ghostel-debug.el ends here